1968 AHSME Problems/Problem 27: Difference between revisions
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== Solution == | == Solution == | ||
<math>\fbox{B}</math> | <math>\fbox{B}</math> | ||
It's easy to calculate that if <math>n</math> is even, <math>Sn</math> is negative <math>n</math> over <math>2</math>. If <math>n</math> is odd then <math>Sn</math> is <math>(n+1)/2</math>. | |||
Therefore, we know <math>S(17) + S(33) + S(50) =9+17-25, which is </math>\fbox{B}$. | |||
== See also == | == See also == | ||
Revision as of 23:37, 17 September 2018
Problem
Let 
, where 
. Then 
equals:
Solution
It's easy to calculate that if 
is even, 
is negative over 
. If is odd then is 
.
Therefore, we know 
\fbox{B}$.
See also
| 1968 AHSME (Problems • Answer Key • Resources) | ||
| Preceded by Problem 26 |
Followed by Problem 28 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 • 26 • 27 • 28 • 29 • 30 | ||
| All AHSME Problems and Solutions | ||
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